The fabrication of electrical circuits, such as printed circuit boards, interconnect devices and flat panel displays, typically includes an automated optical inspection operation. Automated optical inspection typically identifies a collection of candidate defects, including both actual defects and false defects. Following automated optical inspection, a panel containing electrical circuit patterns is supplied to a verification station whereat candidate defects are evaluated and then identified as being either a actual defect or a false defect. Where possible, actual defects are repaired.
False defects include, for example, both random false defects and recurring false defects. Random false defects include, for example, dust and oxidation. Recurring false defects include, for example, geometric pattern anomalies that are repeated throughout a batch of patterns to be inspected. Although the recurring false defects deviate from an ideal pattern to be detected as a defect, they are not sufficiently deviant to be categorized as an actual defect requiring subsequent repair.
Many candidate defects are quickly categorized during manual defect verification as false defects, for example geometric deviations in shape. Other candidate defects require additional time during manual verification in order to determine whether they are a random defect or a recurring defect. Some random defects, for example short circuits, require even more additional time to effect repair of the defect.